Speed of Sound vs Light - Possible?

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Discussion Overview

The discussion revolves around the possibility of achieving sound speeds comparable to the speed of light in various media. Participants explore the relationships between sound velocity, temperature, and density, as well as theoretical scenarios such as conditions inside a black hole.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant states that the velocity of sound in dry air is 332 m/s and suggests that it could increase with density, questioning the feasibility of reaching light speed.
  • Another participant asserts that it is not possible to reach the speed of light with sound.
  • Some participants clarify that the velocity of sound in air is primarily related to temperature rather than density.
  • One participant introduces the equation for sound speed in solids, linking it to Young's modulus and density.
  • Another participant proposes that sound could theoretically reach light speed inside a black hole, but questions the practicality of such conditions in the known universe.
  • There is a discussion about the effects of temperature and density on sound speed, with some participants arguing that while density can influence sound speed, it does not linearly correlate.
  • One participant mentions the exclusion principle from chemistry, suggesting that even with increased density, sound speed has inherent limits due to particle interactions.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between sound speed, temperature, and density, with no consensus on the possibility of achieving sound speeds equal to light speed. Some participants agree that temperature plays a significant role, while others emphasize the importance of density.

Contextual Notes

Participants note that the relationship between sound speed and density is complex and not strictly linear, with various factors influencing the speed of sound in different media. There are also references to theoretical scenarios that may not apply to typical conditions.

Who May Find This Useful

This discussion may be of interest to those studying acoustics, material science, or theoretical physics, particularly in understanding the factors affecting sound propagation in different media.

aman malik
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velocity of sound in dry air is 332m/s and it (linearly-i think so) increases with density.
so is it possible to formulate such a medium in which speed of sound reaches to the level of light
 
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No its not possible
 
Velocity of sound in the air is related to temperature, not density.
 
Yea and the speed of sound in a solid is actually depenadant on the material's youngs modulus by the equation :

V = sqrt(Y/P)

Where Y and P stand for the youngs modulus and the density respectively.
The youngs modulus is the ratio between the stress and strain coefficients of the material.
 
It can be the case inside a black hole.
 
pixel01 said:
It can be the case inside a black hole.

But if you take the known mass of the Universe and it's known dimensions we might well be in a black hole, and it's not true here either...

OP: The answer is No. If you messed with the air in terms of temperature and solidity to make your hypothesis possible it wouldn't be air any more. Specifically to counter the density and modulus problems you would have to freeze the air to zero Kelvin. At which point it wouldn't be air, but pretty much neutronium on it's way to becoming a black hole. Then it would work per the previous poster. Then it would blow up in your face and take a good chunk of the solar system with it per Stephen Hawking.

~sigh~ So many ideas. So few solar systems worth blowing up...
 
one more thing i know now is that the velocity of sound does not linearly vary with medium. can anybody tell me how does it vary?

to jeff reid's ans it varies both with temp and density.
 
  • #10
Jeff Reid said:
Speed of sound in air, not an ideal gas:

Doesn't matter...


This calculation is usually accurate enough, but for great precision one must examine the more general relationship for sound speed in gases.

Source: http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe.html


...In a real material, the stiffness of the springs is called the elastic modulus, and the mass corresponds to the density. All other things being equal, sound will travel more slowly in denser materials, and faster in stiffer ones. For instance, sound will travel faster in iron than uranium, and faster in hydrogen than nitrogen, due to the lower density of the first material of each set...

Source: http://en.wikipedia.org/wiki/Speed_of_sound


I do agree with you that the overall effect of the density as it relates to the speed of sound in air is negligible. However, it technically should be considered from a theoretical stand point.
 
  • #11
in a solid medium sound is tranferred br the vibrtaion of the atoms .more denser the substance more quickly the will tranfer energy from one part to another.
all the links that you have given relate velocity of sound in air, or ideal gases .but which exactly relates with density?
 
  • #12
aman malik said:
velocity of sound in dry air is 332m/s and it (linearly-i think so) increases with density.
so is it possible to formulate such a medium in which speed of sound reaches to the level of light

Take water and air for example. The speed of sound is faster in water than in air because the particles responsible for transmitting the sound energy from point to point is closer to each other. Therefore it's partially correct to say that increasing density of a material will increase the speed of sound, but difficult to attain speed of light because you have to consider the type of particles involved. Even if you use the smallest atomic particle, it still has a certain limit to be compressed in order to conduct sound energy at speed of light. Exclusion principle from Chemistry states that no two electron occupies the same quantum state, meaning there is always a difference in position. In short, the speed of sound only tends to speed of light when density increases. Similarly, increasing temperature has the same effect as the abovementioned.
 

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